The translatable metallothionein mRNA content of liver intestine and kidney will be examined using a wheat germ, cell free portein synthesizing system. A 3H-cDNA has been constructed from purified liver metallothionein mRNA. This will be used as a probe to examine the number of metallothionein mRNA sequences in a variety of tissue extracts following changes in dietary zinc and hormonal status. The antagonistic aspects of copper and zinc absorption will be examined using the isolated, vascularly perfused rat intestinal system. The hormonal induction of the metallothionein system will be examined and integrated into various parameters of intermediary metabolism.